base on 🚄 FASTJSON2 is a Java JSON library with excellent performance. [](https://github.com/alibaba/fastjson2/actions/workflows/ci.yaml) [](https://codecov.io/gh/alibaba/fastjson2/branch/main) [](https://search.maven.org/artifact/com.alibaba.fastjson2/fastjson2) [](https://github.com/alibaba/fastjson2/releases) [](https://openjdk.java.net/) [](https://www.apache.org/licenses/LICENSE-2.0.html) [](https://gitpod.io/#https://github.com/alibaba/fastjson2) [](https://oss.sonatype.org/content/repositories/snapshots/com/alibaba/fastjson2/) [](https://github.com/alibaba/fastjson2/stargazers) [](https://github.com/alibaba/fastjson2/fork) [](https://github.com/alibaba/fastjson2/network/dependents) [](https://github.com/alibaba/fastjson2/graphs/contributors) ##### [📖 English Documentation](README_EN.md) | 📖 中文文档 ##### 本项目的Issues会被同步沉淀至[阿里云开发者社区](https://developer.aliyun.com/ask/) # FASTJSON v2 `FASTJSON 2`是一个性能极致并且简单易用的Java JSON库。 - `FASTJSON 2`是`FASTJSON`项目的重要升级，和FASTJSON 1相比，性能有非常大的提升，解决了autoType功能因为兼容和白名单的安全性问题。 - 性能极致，性能远超过其他流行JSON库，包括jackson/gson/org.json，性能数据: [https://github.com/alibaba/fastjson2/wiki/fastjson_benchmark](https://github.com/alibaba/fastjson2/wiki/fastjson_benchmark) - 支持JDK新特性，包括`JDK 11`/`JDK 17`，针对`compact string`优化，支持Record，支持`GraalVM Native-Image` - 完善的[`JSONPath`](https://alibaba.github.io/fastjson2/jsonpath_cn)支持，支持[SQL:2016](https://en.wikipedia.org/wiki/SQL:2016)的JSONPath语法 - 支持`Android 8+`，客户端和服务器一套API - 支持`Kotlin` [https://alibaba.github.io/fastjson2/kotlin_cn](https://alibaba.github.io/fastjson2/kotlin_cn) - 支持`JSON Schema` [https://alibaba.github.io/fastjson2/json_schema_cn](https://alibaba.github.io/fastjson2/json_schema_cn) - 新增加支持二进制格式JSONB [https://alibaba.github.io/fastjson2/jsonb_format_cn](https://alibaba.github.io/fastjson2/jsonb_format_cn)  # 1. 使用准备 ## 1.1 添加依赖 在`fastjson v2`中，`groupId`和`1.x`不一样，是`com.alibaba.fastjson2`： `Maven`: ```xml <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2</artifactId> <version>2.0.56</version> </dependency> ``` `Gradle`: ```groovy dependencies { implementation 'com.alibaba.fastjson2:fastjson2:2.0.56' } ``` 可以在 [maven.org](https://search.maven.org/artifact/com.alibaba.fastjson2/fastjson2) 查看最新可用的版本。 ## 1.2 其他模块 ### `Fastjson v1`兼容模块 如果原来使用`fastjson 1.2.x`版本，可以使用兼容包，兼容包不能保证100%兼容，请仔细测试验证，发现问题请及时反馈。 `Maven`: ```xml <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>2.0.56</version> </dependency> ``` `Gradle`: ```groovy dependencies { implementation 'com.alibaba:fastjson:2.0.56' } ``` ### `Fastjson Kotlin`集成模块 如果项目使用`Kotlin`，可以使用`fastjson-kotlin`模块，使用方式上采用`kotlin`的特性。 * `Maven`: ```xml <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2-kotlin</artifactId> <version>2.0.56</version> </dependency> ``` 酌情添加标准库(kotlin-stdlib)、反射库(kotlin-reflect)， 其中若使用数据类(data class)、通过构造函数传入参数则添加反射库。 ```xml <dependency> <groupId>org.jetbrains.kotlin</groupId> <artifactId>kotlin-stdlib</artifactId> <version>${kotlin-version}</version> </dependency> <dependency> <groupId>org.jetbrains.kotlin</groupId> <artifactId>kotlin-reflect</artifactId> <version>${kotlin-version}</version> </dependency> ``` * `Kotlin Gradle`: ```kotlin dependencies { implementation("com.alibaba.fastjson2:fastjson2-kotlin:2.0.56") } ``` ```kotlin dependencies { implementation("org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version") implementation("org.jetbrains.kotlin:kotlin-reflect:$kotlin_version") } ``` ### `Fastjson Extension`扩展模块 如果项目使用`SpringFramework`等框架，可以使用`fastjson-extension`模块，使用方式参考 [SpringFramework Support](docs/spring_support_cn.md)。 `Maven`: ```xml <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2-extension-spring5</artifactId> <version>2.0.56</version> </dependency> ``` ```xml <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2-extension-spring6</artifactId> <version>2.0.56</version> </dependency> ``` `Gradle`: ```groovy dependencies { implementation 'com.alibaba.fastjson2:fastjson2-extension-spring5:2.0.56' } ``` ```groovy dependencies { implementation 'com.alibaba.fastjson2:fastjson2-extension-spring6:2.0.56' } ``` # 2. 简单使用 在`fastjson v2`中，`package`和`1.x`不一样，是`com.alibaba.fastjson2`。如果你之前用的是`fastjson1`，大多数情况直接更包名就即可。 ### 2.1 将`JSON`解析为`JSONObject` `Java`: ```java String text = "..."; JSONObject data = JSON.parseObject(text); byte[] bytes = ...; JSONObject data = JSON.parseObject(bytes); ``` `Kotlin`: ```kotlin import com.alibaba.fastjson2.* val text = ... // String val data = text.parseObject() val bytes = ... // ByteArray val data = bytes.parseObject() // JSONObject ``` ### 2.2 将`JSON`解析为`JSONArray` `Java`: ```java String text = "..."; JSONArray data = JSON.parseArray(text); ``` `Kotlin`: ```kotlin import com.alibaba.fastjson2.* val text = ... // String val data = text.parseArray() // JSONArray ``` ### 2.3 将`JSON`解析为`Java`对象 `Java`: ```java String text = "..."; User data = JSON.parseObject(text, User.class); ``` `Kotlin`: ```kotlin import com.alibaba.fastjson2.* val text = ... // String val data = text.to<User>() // User val data = text.parseObject<User>() // User ``` ### 2.4 将`Java`对象序列化为`JSON` `Java`: ```java Object data = "..."; String text = JSON.toJSONString(data); byte[] text = JSON.toJSONBytes(data); ``` `Kotlin`: ```kotlin import com.alibaba.fastjson2.* val data = ... // Any val text = data.toJSONString() // String val bytes = data.toJSONByteArray() // ByteArray ``` ### 2.5 使用`JSONObject`、`JSONArray` #### 2.5.1 获取简单属性 ```java String text = "{\"id\": 2,\"name\": \"fastjson2\"}"; JSONObject obj = JSON.parseObject(text); int id = obj.getIntValue("id"); String name = obj.getString("name"); ``` ```java String text = "[2, \"fastjson2\"]"; JSONArray array = JSON.parseArray(text); int id = array.getIntValue(0); String name = array.getString(1); ``` #### 2.5.2 读取`JavaBean` `Java`: ```java JSONArray array = ... JSONObject obj = ... User user = array.getObject(0, User.class); User user = obj.getObject("key", User.class); ``` `Kotlin`: ```kotlin val array = ... // JSONArray val obj = ... // JSONObject val user = array.to<User>(0) val user = obj.to<User>("key") ``` #### 2.5.3 转为`JavaBean` `Java`: ```java JSONArray array = ... JSONObject obj = ... User user = obj.toJavaObject(User.class); List<User> users = array.toJavaList(User.class); ``` `Kotlin`: ```kotlin val array = ... // JSONArray val obj = ... // JSONObject val user = obj.to<User>() // User val users = array.toList<User>() // List<User> ``` ### 2.6 将`JavaBean`对象序列化为`JSON` `Java`: ```java class User { public int id; public String name; } User user = new User(); user.id = 2; user.name = "FastJson2"; String text = JSON.toJSONString(user); byte[] bytes = JSON.toJSONBytes(user); ``` `Kotlin`: ```kotlin class User( var id: Int, var name: String ) val user = User() user.id = 2 user.name = "FastJson2" val text = user.toJSONString() // String val bytes = user.toJSONByteArray() // ByteArray ``` 序列化结果: ```json { "id" : 2, "name" : "FastJson2" } ``` # 3. 进阶使用 ### 3.1 使用`JSONB` #### 3.1.1 将`JavaBean`对象序列化`JSONB` ```java User user = ...; byte[] bytes = JSONB.toBytes(user); byte[] bytes = JSONB.toBytes(user, JSONWriter.Feature.BeanToArray); ``` #### 3.1.2 将`JSONB`数据解析为`JavaBean` ```java byte[] bytes = ... User user = JSONB.parseObject(bytes, User.class); User user = JSONB.parseObject(bytes, User.class, JSONReader.Feature.SupportBeanArrayMapping); ``` ### 3.2 使用`JSONPath` #### 3.2.1 使用`JSONPath`读取部分数据 ```java String text = ...; JSONPath path = JSONPath.of("$.id"); // 缓存起来重复使用能提升性能 JSONReader parser = JSONReader.of(text); Object result = path.extract(parser); ``` #### 3.2.2 使用`JSONPath`读取部分`byte[]`的数据 ```java byte[] bytes = ...; JSONPath path = JSONPath.of("$.id"); // 缓存起来重复使用能提升性能 JSONReader parser = JSONReader.of(bytes); Object result = path.extract(parser); ``` #### 3.2.3 使用`JSONPath`读取部分`byte[]`的数据 ```java byte[] bytes = ...; JSONPath path = JSONPath.of("$.id"); // 缓存起来重复使用能提升性能 JSONReader parser = JSONReader.ofJSONB(bytes); // 注意这里使用ofJSONB方法 Object result = path.extract(parser); ``` ## Star History [](https://star-history.com/#alibaba/fastjson2) ", Assign "at most 3 tags" to the expected json: {"id":"1988","tags":[]} "only from the tags list I provide: [{"id":77,"name":"3d"},{"id":89,"name":"agent"},{"id":17,"name":"ai"},{"id":54,"name":"algorithm"},{"id":24,"name":"api"},{"id":44,"name":"authentication"},{"id":3,"name":"aws"},{"id":27,"name":"backend"},{"id":60,"name":"benchmark"},{"id":72,"name":"best-practices"},{"id":39,"name":"bitcoin"},{"id":37,"name":"blockchain"},{"id":1,"name":"blog"},{"id":45,"name":"bundler"},{"id":58,"name":"cache"},{"id":21,"name":"chat"},{"id":49,"name":"cicd"},{"id":4,"name":"cli"},{"id":64,"name":"cloud-native"},{"id":48,"name":"cms"},{"id":61,"name":"compiler"},{"id":68,"name":"containerization"},{"id":92,"name":"crm"},{"id":34,"name":"data"},{"id":47,"name":"database"},{"id":8,"name":"declarative-gui "},{"id":9,"name":"deploy-tool"},{"id":53,"name":"desktop-app"},{"id":6,"name":"dev-exp-lib"},{"id":59,"name":"dev-tool"},{"id":13,"name":"ecommerce"},{"id":26,"name":"editor"},{"id":66,"name":"emulator"},{"id":62,"name":"filesystem"},{"id":80,"name":"finance"},{"id":15,"name":"firmware"},{"id":73,"name":"for-fun"},{"id":2,"name":"framework"},{"id":11,"name":"frontend"},{"id":22,"name":"game"},{"id":81,"name":"game-engine "},{"id":23,"name":"graphql"},{"id":84,"name":"gui"},{"id":91,"name":"http"},{"id":5,"name":"http-client"},{"id":51,"name":"iac"},{"id":30,"name":"ide"},{"id":78,"name":"iot"},{"id":40,"name":"json"},{"id":83,"name":"julian"},{"id":38,"name":"k8s"},{"id":31,"name":"language"},{"id":10,"name":"learning-resource"},{"id":33,"name":"lib"},{"id":41,"name":"linter"},{"id":28,"name":"lms"},{"id":16,"name":"logging"},{"id":76,"name":"low-code"},{"id":90,"name":"message-queue"},{"id":42,"name":"mobile-app"},{"id":18,"name":"monitoring"},{"id":36,"name":"networking"},{"id":7,"name":"node-version"},{"id":55,"name":"nosql"},{"id":57,"name":"observability"},{"id":46,"name":"orm"},{"id":52,"name":"os"},{"id":14,"name":"parser"},{"id":74,"name":"react"},{"id":82,"name":"real-time"},{"id":56,"name":"robot"},{"id":65,"name":"runtime"},{"id":32,"name":"sdk"},{"id":71,"name":"search"},{"id":63,"name":"secrets"},{"id":25,"name":"security"},{"id":85,"name":"server"},{"id":86,"name":"serverless"},{"id":70,"name":"storage"},{"id":75,"name":"system-design"},{"id":79,"name":"terminal"},{"id":29,"name":"testing"},{"id":12,"name":"ui"},{"id":50,"name":"ux"},{"id":88,"name":"video"},{"id":20,"name":"web-app"},{"id":35,"name":"web-server"},{"id":43,"name":"webassembly"},{"id":69,"name":"workflow"},{"id":87,"name":"yaml"}]" returns me the "expected json"